[R] subsetting data-frame by vector of characters

[Chuck Cleland]

On 6/13/2008 10:07 AM, james perkins wrote:
> Hi,
> 
> I have a very simple problem but I can't think how to solve it without 
> using a for loop and creating a large logical vector. However given the 
> nature of the problem I am sure there is a "1-liner" that could do the 
> same thing much more efficiently.
> 
> bascially I have a dataframe with characters in, eg
> 
>  >names.and.numbers
> 
> (index)    Name    Fave.Number
> 1    John    7
> 2    Tony    12
> 3    Phil    14
> 4    Adam    22
> 5    Robert    23
> 
> 
> Now, imagine I have a vector of names, ie:
> 
>  >names = c("John,Phil,Robert")
> 
> All I want to do is get the subset of the dataframe which corresponds to 
> the names in the vector "Names". IE
> 
> (index)    Name    Fave.Number
> 1    John    7
> 2    Phil    14
> 3    Robert    23
> 
> Sorry, I know its trivial but I'm new to R and its hard to start 
> thinking in R, as I say, I've written a complicated for loop using 
> intersect and creating a logical table, but this is very long winded!!!

   How about this:

subset(names.and.numbers, Name %in% mynames)

   where mynames is the vector of names you want?

?subset

?is.element

> Regards,
> 
> Jim
> 
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-- 
Chuck Cleland, Ph.D.
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